The present invention relates to faces masks having improved comfort characteristics.
Wearing protective face masks of various configurations has become standard procedure in the health care and other related fields. The use of a face mask is important to protect both the patient and the health care practitioner. In addition, many industrial applications also require wearing protective face masks.
A vast array of face mask configurations are know to those skilled in the art. Exemplary face masks are described and shown, for example, in the following U.S. Pat. Nos. 4,802,473; 4,969,457; 5,322,061; 5,383,450; 5,553,608; 5,020,533; and 5,813,398.
Much effort has been expended on developing face masks having improved filtration and/or sealing characteristics. For example, the molded mask illustrated and described in U.S. Pat. No. 4,319,567 is especially configured to improve the seal around the edges of the mask. Pleated face mask designs have also been configured to improve the fit of the face mask, thereby attempting to reduce the passage of liquids and/or aerosols between the periphery of the mask and the wearer""s face. Other designs sought to improve the seal around the wearer""s face by using fluid-impervious flaps as disclosed in U.S. Pat. No. 5,553,608, and foam or adhesive tape placed around the periphery of the mask as described in U.S. Pat. No. 5,735,270.
Improvements in filtration and sealing characteristics of a mask do not necessarily result in increased comfort and fit of the mask. While some advances have been made, improvement is still desirable with respect to comfort enhancing features of face masks. For instance, a primary complaint of wearers of face masks is that use of the mask for extended periods of time results in abrasion across the face at the contact points between the face mask and the wearer""s skin, and more particularly, along the periphery of the mask. Such abrasion leads to chaffing and redness accompanied by discomfort. Thus, there exists a need for a face mask that maintains barrier properties while providing improved comfort to the wearer.
Objects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.
The present invention relates to a face mask that provides enhanced comfort to the wearer while maintaining its barrier properties. The invention is not limited to any particular style or configuration of face mask, and includes rectangular masks, pleated masks, duck bill masks, cone masks, trapezoidal masks, etc. It should be appreciated that the benefits of the present invention can be incorporated into a variety of face mask configurations.
In accordance with the invention, the mask portion of the face mask includes at least one material having stretch and recovery characteristics so that the mask portion overall is extensible and retractable in one or more directions. A mask portion that is extensible and retractable in at least two directions is able to stretch across the face of the wearer from ear to ear and from nose to chin. This ability to extend and retract creates a better seal around the periphery of the mask portion and a more comfortable fit for the wearer.
The mask portion may be sized to fit over the nose, mouth, and/or cheeks of the wearer as desired. For example, with a generally rectangular mask, the mask portion has a top edge and a bottom edge, with the top edge adapted to fit over the nose and cheeks of the wearer and the bottom edge adapted to extend under the chin of the wearer. The mask portion may be a composite of several layers, at least one of which imparts the desired extensible and retractable characteristics to the mask portion.
The mask portion may include an outer layer, a layer having stretch and recovery characteristics (the xe2x80x9cstretch and recoveryxe2x80x9d layer), a filtration layer, and an inner layer. The layers of the mask portion may be constructed from various conventional materials. For example, the inner layer and the outer layer may be a nonwoven material, such as a spunbonded, meltblown, or coform nonwoven web or a bonded carded web. The nonwoven material may be a necked material or a reversibly necked material. The inner layer and the outer layer may be made of the same material or different materials. The filtration layer may be a meltblown nonwoven web, and may more particularly be an electret. The filtration layer may alternatively be an expanded polytetrafluoroethylene membrane. In some embodiments, the filtration layer may have stretch and recovery characteristics, eliminating the need for an additional stretch and recovery layer. The layers of the composite may be joined by various methods, including adhesive bonding, stitchbonding, thermal bonding, or ultrasonic bonding, provided that the resulting composite is extensible and retractable.
The stretch and recovery layer may be one or a combination of suitable materials, such as a necked nonwoven web, a reversibly necked nonwoven web, and elastic materials including an elastic coform material, an elastic meltblown nonwoven web, a plurality of elastic filaments, an elastic film, or any combination thereof.
In some embodiments, resilient strips of material may be attached to and extend along each edge of the extensible and retractable mask portion for use in securing the mask to the wearer""s face and to provide an enhanced fluid seal between the periphery of the mask portion and the wearer""s face. The strips may be made of a material that is extensible and retractable to enhance the fit and comfort of the extensible and retractable mask portion.
The present invention may include any manner of element, such as ear loops, a continuous loop, surgical-style tie fasteners, or other elements for securing the mask to the face of the wearer. The securing element may be constructed of extensible and retractable material if desired. Where the mask incorporates resilient edge strips, the tie fasteners, ear loops, or other suitable securing elements may be attached to the respective resilient edge strips adjacent to each side of the mask portion.
A face mask in accordance with the present invention can incorporate any combination of known face mask features. For example, the mask portion may include an elongated malleable member disposed to allow configuring the top edge to closely fit the contours of the nose and cheeks of the wearer. Likewise, the face mask may have any configuration of an eye shield or visor. Further, the face mask may include a beard cover disposed to completely contain the beard of the wearer.
An extensible and retractable filtration composite particularly suited for face mask applications is also within the scope of the present invention. The filtration composite may be a composite of multiple layers or a composite of multiple materials in a single layer. In a multiple layer composite embodiment, the composite may include an outer nonwoven web layer, a stretch and recovery layer (which may be a filtration layer as well), and an inner nonwoven web layer. The stretch and recovery layer may be any material that possess sufficient stretch and recovery characteristics to impart the desired degree of xe2x80x9cextensible and retractablexe2x80x9d to the composite overall, including an elastic coform material, an elastic meltblown nonwoven web, a plurality of elastic filaments, an elastic film, or a combination thereof. The layers of the composite are joined such that the stretch and recovery layer imparts its properties to the overall composite.
As used herein, the term xe2x80x9cnonwoven fabric or webxe2x80x9d means a web having a structure of individual fibers or threads which are interlaid, but not in an identifiable repeatable manner as in a knitted fabric. Nonwoven fabrics or webs have been formed from various processes such as, for example, meltblowing processes, spunbonding processes, and bonded carded web processes. The basis weight of nonwoven fabrics is usually expressed in ounces of material per square yard (osy) or grams per square meter (gsm) and the fiber diameters are usually expressed in microns. (Note that to convert from osy to gsm, multiply osy by 33.91).
As used herein, the term xe2x80x9cspunbonded fibersxe2x80x9d refers to small diameter fibers which are formed by extruding molten thermoplastic material as filaments from a plurality of fine, usually circular capillaries of a spinneret with the diameter of the extruded filaments then being rapidly reduced to fibers as by, for example, in U.S. Pat. No. 4,340,563 to Appel et al., and U.S. Pat. No. 3,692,618 to Dorschner et al., U.S. Pat. No. 3,802,817 to Matsuki et al., U.S. Pat. Nos. 3,338,992 and 3,341,394 to Kinney, U.S. Pat. No. 3,502,763 to Hartman, and U.S. Pat. No. 3,542,615 to Dobo et al., the contents of which are incorporated herein by reference in their entirety. Spunbond fibers are generally continuous and have diameters generally greater than about 7 microns, more particularly, between about 10 and about 20 microns.
As used herein, the term xe2x80x9cmeltblown fibersxe2x80x9d means fibers formed by extruding a molten thermoplastic material through a plurality of fine, usually circular, die capillaries as molten threads or filaments into converging high velocity, usually hot, gas (e.g. air) streams which attenuate the filaments of molten thermoplastic material to reduce their diameter, which may be to microfiber diameter (less than about 75 microns). Thereafter, the meltblown fibers are carried by the high velocity gas stream and are deposited on a collecting surface to form a web of randomly disbursed meltblown fibers. Such a process is disclosed, for example, in U.S. Pat. No. 3,849,241 to Butin et al., the content of which is incorporated herein by reference in its entirety. Meltblown fibers may be continuous or discontinuous.
As used herein, the term xe2x80x9ccompositexe2x80x9d refers to a material which may be a multicomponent material or a multilayer material. These materials may include, for example, stretch bonded laminates, neck bonded laminates, or any combination thereof.
As used herein, the term xe2x80x9cstretch bonded laminatexe2x80x9d refers to a composite material having at least two layers in which one layer is a gatherable layer and the other layer is an elastic layer. The layers are joined together at disparate points when the elastic layer is extended from its original condition so that upon relaxing the layers, the gatherable layer is gathered. Such a multilayer composite elastic material may be stretched to the extent that the nonelastic material gathered between the bond locations allows the elastic material to elongate. One type of stretch bonded laminate is disclosed, for example, by U.S. Pat. No. 4,720,415 to Vander Wielen et al., the content of which is incorporated herein by reference in its entirety. Other composite elastic materials are disclosed in U.S. Pat. No. 4,789,699 to Kieffer et al., U.S. Pat. No. 4,781,966 to Taylor and U.S. Pat. Nos. 4,657,802 and 4,652,487 to Morman and U.S. Pat. No. 4,655,760 to Morman et al., the contents of which are incorporated herein by reference in their entirety.
As used herein, the terms xe2x80x9cneckingxe2x80x9d or xe2x80x9cneck stretchingxe2x80x9d interchangeably refer to a method of elongating a nonwoven fabric, generally in the machine direction, to reduce its width (cross-machine direction) in a controlled manner to a desired amount. The controlled stretching may take place under cool, room temperature or greater temperatures and is limited to an increase in overall dimension in the direction being stretched up to the elongation required to break the fabric, which in most cases is about 1.2 to 1.6 times. When relaxed, the nonwoven fabric retracts toward, but does not return to, its original dimensions such that it is narrower in the cross machine direction. Such a process is disclosed, for example, in U.S. Pat. No. 4,443,513 to Meitner and Notheis, U.S. Pat. Nos. 4,965,122, 4,981,747 and 5,114,781 to Morman and U.S. Pat. No. 5,244,482 to Hassenboehler Jr. et al., the contents of which are incorporated herein by reference in their entirety.
As used herein, the term xe2x80x9cnecked materialxe2x80x9d refers to any material which has undergone a necking or neck stretching process.
As used herein, the term xe2x80x9creversibly necked materialxe2x80x9d refers to a material that possesses stretch and recovery characteristics formed by necking a material, then heating the necked material, and cooling the material. Such a process is disclosed in U.S. Pat. No. 4,965,122 to Morman, commonly assigned to the assignee of the present invention, and incorporated by reference herein in its entirety.
As used herein, the term xe2x80x9cneck bonded laminatexe2x80x9d refers to a composite material having at least two layers in which one layer is a necked, non-elastic layer and the other layer is an elastic layer. The composite is formed by joining the layers while the non-elastic layer is in a necked condition. Examples of neck-bonded laminates are such as those described in U.S. Pat. Nos. 5,226,992, 4,981,747, 4,965,122 and 5,336,545 to Morman, the contents of which are incorporated herein by reference in their entirety.
As used herein, the term xe2x80x9ccoformxe2x80x9d means a meltblown material to which at least one other material is added during the meltblown material formation. The meltblown material may be made of various polymers, including elastomeric polymers. Various additional materials may be added to the meltblown fibers during formation, including, for example, pulp, superabsorbent particles, cellulose or staple fibers. Coform processes are illustrated in commonly assigned U.S. Pat. No. 4,818,464 to Lau and U.S. Pat. No. 4,100,324 to Anderson et al., the contents of which are incorporated herein by reference in their entirety.
As used herein, the term xe2x80x9cstitchbondedxe2x80x9d refers to a process in which materials (fibers, webs, films, etc.) are joined by stitches sewn or knitted through the materials. Examples of such processes are illustrated in U.S. Pat. No. 4,891,957 to Strack et al. and U.S. Pat. No. 4,631,933 to Carey, Jr, the contents of which are incorporated herein by reference in their entirety.
As used herein, the term xe2x80x9cultrasonic bondingxe2x80x9d refers to a process in which materials (fibers, webs, films, etc.) are joined by passing the materials between a sonic horn and anvil roll. An example of such a process is illustrated in U.S. Pat. No. 4,374,888 to Bornslaeger, the content of which is incorporated herein by reference in its entirety.
As used herein, the term xe2x80x9cthermal point bondingxe2x80x9d involves passing materials (fibers, webs, films, etc.) to be bonded between a heated calender roll and an anvil roll. The calender roll is usually, though not always, patterned in some way so that the entire fabric is not bonded across its entire surface, and the anvil roll is usually flat. As a result, various patterns for calender rolls have been developed for functional as well as aesthetic reasons. Typically, the percent bonding area varies from around 10 percent to around 30 percent of the area of the fabric laminate. As is well known in the art, thermal point bonding holds the laminate layers together and imparts integrity to each individual layer by bonding filaments and/or fibers within each layer.
As used herein, the term xe2x80x9celasticxe2x80x9d refers to any material, including a film, fiber, nonwoven web, or combination thereof, which upon application of a biasing force, is stretchable to a stretched, biased length which is at least about 150 percent, or one and a half times, its relaxed, unstretched length, and which will recover at least 15 percent of its elongation upon release of the stretching, biasing force.
As used herein, the term xe2x80x9cextensible and retractablexe2x80x9d refers to the ability of a material to extend upon stretch and retract upon release. Extensible and retractable materials are those which, upon application of a biasing force, are stretchable to a stretched, biased length between 100 percent and about 150 percent of their unstretched length and which will recover a portion, preferably at least about 15 percent, of their elongation upon release of the stretching, biasing force.
As used herein, the terms xe2x80x9celastomerxe2x80x9d or xe2x80x9celastomericxe2x80x9d refer to polymeric materials that have properties of stretchability and recovery.
As used herein, the term xe2x80x9cstretchxe2x80x9d refers to the ability of a material to extend upon application of a biasing force. Percent stretch is the difference between the initial dimension of a material and that same dimension after the material has been stretched or extended following the application of a biasing force. Percent stretch may be expressed as [(stretched lengthxe2x80x94initial sample length)/initial sample length]xc3x97100. For example, if a material having an initial length of one (1) inch is stretched 0.50 inch, that is, to an extended length of 1.50 inches, the material can be said to have a stretch of 50 percent.
As used herein, the term xe2x80x9crecoverxe2x80x9d or xe2x80x9crecoveryxe2x80x9d refers to a contraction of a stretched material upon termination of a biasing force following stretching of the material by application of the biasing force. For example, if a material having a relaxed, unbiased length of one (1) inch is elongated 50 percent by stretching to a length of one and one half (1.5) inches the material would have a stretched length that is 150 percent of its relaxed length. If this exemplary stretched material contracted, that is recovered to a length of one and one tenth (1.1) inches after release of the biasing and stretching force, the material would have recovered 80 percent (0.4 inch) of its elongation.
As used herein, the term xe2x80x9celectretxe2x80x9d or xe2x80x9celectret treatingxe2x80x9d refers to a treatment that imparts a charge to a dielectric material, such as a polyolefin. The charge includes layers of positive or negative charges trapped at or near the surface of the polymer, or charge clouds stored in the bulk of the polymer. The charge also includes polarization charges which are frozen in alignment of the dipoles of the molecules. Methods of subjecting a material to electret treating are well known by those skilled in the art. These methods include, for example, thermal, liquid-contact, electron beam, and corona discharge methods. One particular technique of subjecting a material to electret treating is disclosed in U.S. Pat. No. 5,401,466, the contents of which is herein incorporated in its entirety by reference. This technique involves subjecting a material to a pair of electrical fields wherein the electrical fields have opposite polarities.
As used herein, the term xe2x80x9cpolymerxe2x80x9d generally includes but is not limited to, homopolymers, copolymers, such as for example, block, graft, random and alternating copolymers, terpolymers, etc. and blends and modifications thereof. Furthermore, unless otherwise specifically limited, the term xe2x80x9cpolymerxe2x80x9d shall include all possible geometrical configurations of the molecule. These configurations include, but are not limited to isotactic, syndiotactic and random symmetries.
As used herein, any given range is intended to include any and all lesser included ranges. For example, a range of from 45-90 would also include 50-90; 45-80; 46-89; and the like.